**About the Editor**

**Eulogio Castro** has a Ph.D. in Chemical Engineering from the University of Granada, Spain, where he also worked as a teacher in undergraduate and graduate studies in Chemistry and Chemical Engineering. Since the foundation of the University of Jaen in 1993, he has served as a teacher and ´ researcher, and he is currently a Full Professor of Chemical Engineering. He was also an Invited Researcher at the Institute of Biotechnology in UNAM, Mexico as well as at the Ecole Nationale ´ Superieure de Chimie de Toulouse, France, and a Visiting Assistant Professor at the University of ´ Florida, USA.

His main research interests are focused on the conversion of biomass into added-value products. Different agricultural and agroindustrial materials have been used as raw materials for the development of the biorefinery concept, including sugarcane bagasse, rapeseed straw, brewer spent grains, sunflower stalks and especially all the by-products from olive tree cultivation and those derived from the olive oil production process. Prof. Castro has studied the products, biofuels, renewable chemicals and biomaterials as well as the techno-economic and environmental issues related to biorefinery deployment.

### **Preface to "Biorefinery Based on Olive Biomass"**

Olive tree cultivation is attracting increasing interest worldwide due to the health benefits of olive oil consumption. Currently, more than eleven million hectares of olive trees are spread across sixty countries, with those in the Mediterranean basin being the main olive oil producers. As a consequence of the production of olive oil, a huge amount of biomass is generated yearly, coming from two different origins. On the one hand, the pruning of olive trees produces a grea<sup>t</sup> deal of biomass that must be eliminated from cultivation fields. On the other hand, the olive oil production process is also responsible for the generation of a number of biomasses, such as olive leaves, pits, pomace and even olive-mill wastewater, all of which must be adequately handled. All these biomasses can be exploited as raw materials for the production of a number of biocompounds under the biorefinery scheme. This Special Issue of Bioenergies aims to summarize the recent research carried out about these different biomasses, along with procedures, methods and configurations to obtain a wide range of bioproducts, including but not limited to biofuels, lignin, natural antioxidants, bio-based compounds, fermentable sugars, etc. In addition to the environmental advantages derived from avoiding the usual practices of disposal of such residues (now referred to as by-products), the economic relevance of this proposal is undeniable , even if further research efforts must be accomplished.

The accepted papers deal with virtually all the stages in the exploitation of olive-derived biomass as a feedstock for a biorefinery, from the characterization of the chemical composition (including the bioactive compounds) to the treatment of the final by-products obtained after olive oil production, such as olive-mill wastewater, olive solid residues or even the extracted olive pomace.

This collection of scientific articles is an excellent source of information that can be used as a starting point to develop a further business model beyond the conventional and limited just-olive-oil-producing facility.

I would like to thank the professional staff of MDPI for their efforts that made the Special Issue and this edition possible.

> **Eulogio Castro** *Editor*
